Zeolites are crystalline aluminosilicate molecular sieves which have a microporous three-dimensional framework structure. In general, the crystalline zeolites are formed from corner-sharing AlO.sub.2 and SiO.sub.2 tetrahedra and are characterized by having pore openings of uniform dimensions, having a significant ion-exchange capacity and being capable of reversibly desorbing an adsorbed phase which is dispersed throughout the internal voids of the crystal without significantly displacing any atoms which make up the permanent crystal structure.
Zeolites can be represented on an anhydrous basis, by the empirical formula EQU M.sub.2 /.sub.n O:Al.sub.2 O.sub.3 :XSiO.sub.2
where M is a cation having the valence n, X is generally equal to or greater than 2. In naturally occurring zeolites, M can be Li, Na, Ca, K, Mg and Ba. The M cations are loosely bound to the structure and frequently can be completely or partially replaced with other cations by conventional ion exchange techniques. Currently over 100 species of both naturally occurring and synthetic zeoetes are known. One notes that although most commercial patents refer to these phosphate compositions as "molecular sieves" rather than zeolites, scientific groups include them in the "zeolites" (Barrer, Pure and Applied Chem., v. 51, 1091 (1979); Coombs et. al., Canad. Mineral, v. 35, p. 1571 (1997)).
Other crystalline microporous compositions are known which have been called zeolites or molecular sieves and which exhibit the ion-exchange and/or adsorption characteristics of the zeolites. These include aluminophosphates and substituted aluminophosphates as disclosed in U.S. Pat. Nos. 4,310,440 and 4,440,871. U.S. Pat. No. 4,440,871 discloses a class of silica aluminophosphates which are identified by the acronym SAPO and which have different structures as identified by their x-ray diffraction pattern. The structures are identified by a numerical number after ALPO, SAPO, MEAPO, etc. (Flanigen et al, Proc. 7th Int. Zeolite Conf., p. 103 (1986) and may include Al and P substitutions by Si, Be, Mg, Ge, Zn, Fe, Co, Ni, etc. The present invention is the first synthesis of a phosphate (ALPO/SAPO, etc.) having the characteristic X-ray diffraction pattern shown in Table 1.